Commutator for dynamo-electric machines



(No Model.) 2 sheetssheet 1.

v THOMSON. OOMMUTATORFOR-D'YNAMO ELECTRIC MACHINES. No. 523,019.Patented July 17,1894.

ms was mus co. mom-amen WASNINGTDN u c (No Model.) 2 Sheets Sheet 2.

E. THOMSON.

v GOMMUTATOR FOR DYNAMO ELECTRIC MACHINES.

Patented Ju1y17, 1894.

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UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF SWAMPSGOTT, MASSACHUSETTS, ASSIGNOR TO THE GENERALELECTRIC COMPANY OF NEW YORK.

COMMUTATOR FOR DYNAMO-ELECT'RIC MACHINES.

I SPECIFICATION forming part of Letters Patent No. 523,019, dated July17, 1894.

Application filed February 10, 1894. Serial No. 499,717. (No model.)

To all whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, and aresident of Swampscott, county of Essex, State of Massachusetts, haveinvented certain new and useful Improvements in Commntators forDynamo-Electric Machines, of which the followmg is a specification.

My invention relates to commutators for dynamo-electric machines, andhas for its object to provide a ready means of renewing the insulationbetween the segments or of correcting the defects in the face of thecommutator by removing a few of its segments without turning down theWhole commutator; to which ends I divide the commutator into a set ofsub-segments and a set of wearing or surface-segments upon which thebrushes bear, and insulate the various parts from one another in a waymore particularly described hereinafter.

lVhen a single spot or segment upon a commutator is softer than thesurrounding parts, it wears away slightly, making what is termed a fiatupon the commutator surface; as the brushes pass over this flat spot,they are apt to jump and leave the surface of the commutator, which isusually revolved at a somewhat high s'peed, and these jumps orirregularities produce more or less sparking, which being concentratedat a particular point, further increases the difficulty until eventuallyit is necessary to turn down the commutator until the bottom of the flatis, reached; thus a large part of the copper in the commutator may beturned off and wasted to correct a small defect. This wasteful procedurehas led to the adoption of the expedient I have named, that is, ofmaking the commutator in two portions or sets of segments, one of thesesecured rigidly in place and having the leads from the armature coilsfastened to it permanently, if desired, while the second set of segmentsis secured to the first in any suitable manner, and formsawearingsurface for the commutator; when a fiat develops in one of these wearingsegments, it may be at once corrected by removing the segment affected,or where the insulation between the adjoining segments has also becomeinjured, by removing two or three of these wearing segments andsubstituting new ones, then turning down these segments of thecommutator to the size of the old parts; a great portion of the expenseattending upon repairs is thus obviated, and it is many times possibleto repair the commutator without sending it back to the factory orthrowing the machine out of use except for a short time. While thisprocedure has great advantages, it has been found difficult toefficiently insulate the wearing segments, and it is to this particulardifficulty that my present invention is addressed, it being exemplifiedin the annexeddrawings forming part of this specification, and thenovelty being pointed out in the claims.

In the drawings, Figure 1 is a longitudinal section of a commutatorembodying my invention. Fig. 2 is an end elevation partly in section ofthe part shown in Fig. 1. Fig. 3 is a single segment and wearing segmentshown separately. Fig. 4 shows two arrangements of the insulatingmaterial, the segments being shownin section. Figs. 5, 6, 9, 10, and 11show various shapes of insulating material. Figs. 7 and 8 are plan viewsof sub segments. Fig. 12 shows two additional modes of placing theinsulation. Fig. 13 is a view in elevation of a commutator partly inlongitudinal section, showing a means for. mounting the segments on theshaft. Fig. 14: is a view of the commutator in Fig. 13, showing thewearing segments removed, and Fig. 15 is a detail view partly insection, of a complete mounted segment.

In Figs. 1 and 2, S, S, &c., are the sub-segments mounted, as shown,upon commutator sleeves surrounding the shaft, with interposedinsulation, shown in heavy black lines.

-Lugs or extensions are provided at L with openings for the attachmentof the armature leads, which may be soldered or otherwise fastened tothe segments.

W, W, represent wearing segments, part of I which are shown in sectionin the upperright hand part of Fig. 2. These wearing segments aresecured by screws, V, V, to the sub segments. The insulation between thewearing segments fills not only the space between the two adjacentsegments but also the space between the wearing segment and thesub-segment; this spacebein g formed by cutting away the face of thesub-segment S at t, or cutting away the under side of the wearingsegment, or both, and being more distinctly seen in Fig. 3, where asingle segment is shown separately for clcarness of illustration, thesubsegment S being of different shape from that shown in Figs. 1 and 2.

There are several ways in which the insulation between the wearingsegments may be applied. Two of these ways are illustrated in Fig. 4wherein the right half of the figure is shown with the insulatingmaterial I, I, in heavy black, wrapped around the under side of thewearing segment and projecting up at the sides. In this case half thesegments, as 'W', VV', W, the, would be attached to the sub-segments byscrews without any insulating material, while the remaining bars, "W,\V, &c., would have the insulating material made in channel form andplaced in position under the segment while it is being drawn down intoplace; by which c0nstruction the insulating material takes its positionor forms itself between the adjacent segments and is held in place bypassing underneath one half of them. In the left part of Fig. at I showthe more obvious arrangement of putting the insulation under each of thesegments W N and drawing them down into place. This gives a doublethickness between the segments, and the insulation would be made of halfthickness. The insulating material may be mica or mica paper sheets orlayers superimposed and bent into form for use, or bent during the actof placing it into position, or any other suitable material. The inneredges of the wearing segments should be rounded where the insulationturns a corner, and I prefer to cut it away underneath the wearingsegments where the screws pass through, so as to get a good metallicbearing independently of any variation of thickness in the insulationbetween the sub'segments and the wearing segments, thus insuring ampleelectrical contactalso. The sub-segments may, of course, be made ofmetal different from that of the wearing segments.

The shape of the pieces of insulation which would be used is indicatedin Fig. 5, where the pieces are shown flat, and the dotted linesindicate the places of bending to form.

In Fig. 5 the spaces or notches a, a, are for the passage of the screwsthat unite the wearing segments to the sub-segments, while the part 1)underlies the wearing segments.

In Fig. 6 I show that the piece may be made of two halves each of whichis bent on a dotted line to form the portion b which goes under thewearing segment. In this case the pieces on end would be of t. form withedges meeting under the segment, as at I in Fig. at.

Fig. 7 is a top view of such a segment as is used in Fig 1, where a arepresent surfaces in which the screw holes are tapped, and which matchthe notches a, a, of the piece Fig. 5, while '6 is the cutaway portionwhich re ceives the bridge part Z) underlying the wean ing segment.

Figs 8 and i) show a segment and insulating piece respectively, in whichthere is an extra bearing surface a on the segment and an e :-ctraopening a in the insulating piece, and n like manner this insulatingpiece may, as in Fig.10,be composed of two halves corresponding to Fig.6. The portions 1;,1), of the insulating piece which underlie thewearing seg ment may be, as shown in Fig. ll overlapped; thatis, thepieces may be made of bent plates of insulation, the parts under thesegments being doubled by overlapping of two extensions from aninsulating piece on each side 0]. the wearing segment.

As shown in theleftof Fig. 19,thoinsulating pieces I 1 under the wearingsegments NV, \V, the, are bent into an L shape, as seen on end, and thisis a convenientway of arranging the insulation.

In Fig. 12, on the right, the insnlatlng pieces 1, I, are, as in Fig.ll,bent under the segments 'W, \V,d:c.,and there form a doublethickness; that is, the pieces on each side of the segment lap under it,one above the other, while the pieces between the segments are doubled,one passing under the segment to the right and the other to the left.

Instead of holding the suh-segn'ients to the commutator in the usual wayby taperlng their ends and clamping them endwise, I have devised amethod suitable to the practice of my invention which is shown in Figs.13, l-t and 15, and which consists in arranging, as shown in Figs. 13and 14-, the sub'segmeuts with a sleeve or support Z secured upon theshaft X, there being a layer of insulating material, as shown at I, i,underlying the subsegments or supporting segments S, S, and the sleeve75. The sub-segments S are assembled around the sleeve Z which may havea slight expansion, as at e, entering into a cor: responding internalgroove in. the range oi: sub-segments S for the purpose of preventingend motion of the segments on the sleeve 71. Any other means might beused for the same purpose and the expansion 6 is by no means essentialto be used where the"subsegntcnts.

S, S, are bound iirmly to the underlying sleeve or to the shaft. To holdthe sub-segments in place I cut a deep groove, one or more, around thesaid body of segments and insulate the inside of the groove, asindicated at I, for the reception of a binding wire, or a band of anysuitable character. This might be a hard unelastic cord cemented inplace, or the binding may be composed of wire, iii-- sulated or not,laid on with considerable tension and forming a complete metallicbinding holding the segments 8,3, in place, or the binding B might bereplaced by strips or rings made in sections and drawn togi'zther in anysuitable fashion.

With the binding 13 in place the segments, as is evident, will be helddown firmly and yet;

ICS

insulated from each other, as the binding B does not touch any of them.In other respects said segments are the same as those in Figs. 1 and 2,and may have the wearing portion mounted thereon in the same way, andinsulated from each other in the ways pointed out in the prior figures.

It is desirable, as indicated in Figs. 13 and 14, to cover up the end ofthe sub-segments by a ring of insulating material W, shown as c0v eringonly a single end of the sub-segments. The other end, or the onecarrying the lugs for the attachment of the armature leads, can likewisebe protected by a ring of insulating material.

In Fig. 15 there is shown a preferable arrangement of the band B, whichin this case, if made of conducting material, is entirely inclosed in aninsulating casing, or separated by insulation, top, bottom, and sides,whereby any leakage from one segment to the band and from the band toany other segment is prevented. Space, in each case, is of course alwaysleft underneath the wearing segments for the passage of its ownparticular insulating'sheet when bent inward, as described in the formerfigures. Minor variations from these arrangements are made while notdeparting from the essence of my invention.

What I claim as new, and desire to secure by Letters Patent'of theUnited States, is

1. In a commutator for dynamo-electric machines or motors, a supportingbody, sub-segments carried by such supporting body and insulatedtherefrom, each sub-segment being provided also with a wearing segmentmechanically and electrically connected thereto, such wearing segmentsprovided with insulation distinct from that of the sub-segments.

2. In a commutator for a dynamo-electric machine or motor, a supportingbody, a series of sub-segments insulated from the support ing body andfrom each other, each sub-segment having a cut-away portion as t, aseries of wearing segments attached to the sub-segments, and insulationof L-shaped cross-section arranged between the wearing segments andextending into the cut-away portion of the sub-segments; whereby singlewearing segments may be removed and reinsulated without disturbing oraffecting the insulation of the other segments.

3. In a commutator for a dynamo-electric machine or motor, a series ofsub-segments insulated from each other in combination with a series ofwearing segments correspond ng to the sub-segments, and strips ofinsulation between the adjoining wearing segments, said strips turnedunder the wearing segments and thereby prevented from escape during therotation of the commutator.

4. A commutator having sub-segments and removable wearing segmentscorresponding thereto, and insulating strips passing under alternatewearing segments, the edges of which strips are located between theadjacent wearing segments for insulating them from each other.

5. In a com mutator, a series of sub-segments surrounded by a band,insulated as described, whereby said sub-segments are held in place, incombination with an outer set of wearing segments secured to thesub-segments.

6. In a commutator, a set of sub-segments secured from expansionradially by a surrounding insulated band, one or more, together with aset of wearing segments insulated from each other by strips ofinsulating material which turn under the wearing segments.

7. In a commutator, a supporting sleeve or shaft surrounded by a layerof insulating material upon which are carried sub-segments insulatedlaterally from each other and held in place by a band or ring suitablyinsulated from the sub-segments, and a set of wearing segments removableat will and insulated from each other by strips of insulating material,which bands turn under said wearing segments.

In witness whereof I have hereunto set my hand this 8th day of February,1894.

ELIHU THOMSON.

Witnesses:

JOHN W. GIBBONEY, BENJAMIN B. HULL.

